Method and device for fibrillating a strip-like flat textile structure by subjecting it to a high-pressure liquid

ABSTRACT

For fibrillating a continuously conveyed, textile sheet material ( 3 ) a fluid under high pressure is delivered through a wide-slot nozzle ( 6 ) as a continuous fluid curtain ( 14 ) onto the sheet material ( 3 ). With this gentle way of fibrillating all types of fabrics may be fibrillated, in particular also light materials. The wide-slot nozzle ( 6 ) can be manufactured simply and inexpensively.

The invention relates to a method and a device for fibrillating aweb-like, textile sheet material. It thus belongs very generally to thefield of textile finishing.

With the term “fibrillating” the production of short fibre pieces,so-called micro-fibres, on the surface of the fibres constituting thesheet material is described. The micro-fibrils are the result ofmechanical, enzymatic and/or chemical treatment of the textile sheetmaterial. By way of this a “silk-like” feel is achieved. The “peachskin” or “patina” which thus arises gives the sheet material an improveddrape and look. For fibrillating textile sheet material various methodsand devices are known, e.g. with the aid of granular grinding means,such as sand paper or diamond paper, or by way of rotating brushes.

One method for fibrillating by way of impacting the textile sheetmaterial with high pressure fluid is the subject-matter of WO97/19213.With this high pressure fluid exits a multitude of closely placedopenings onto the continuously conveyed textile material sheet. Themanufacture of a nozzle with such openings is complicated. Furthermorethe small diameter of the openings and their small mutual distance leadto a blocking of the bores by way of deposits of dissolve salts andcontaminants in the high pressure fluid. The fluid jets separated fromone another exiting the openings may furthermore lead to an irregular,stripe-like fibrillation of the web-like textile sheet material.

It is therefore the object of the present invention to make available amethod and a device for fibrillating web-like textile sheet material byway of impacting with high pressure fluid, which avoid the disadvantagesof that which exists.

In the document U.S. Pat. No. 4,152,480 there is described a method inwhich a continuously conveyed, web-like textile sheet material isimpacted with high pressure fluid delivered through a wide-slot nozzle.By way of this the individual fibres of the textile sheet material areto be intertwined or matted with one another in order to produce afleece-like product.

A similar method with a wide-slot nozzle may also be applied forfibrillating a textile sheet material if the fluid is led to thewide-slot nozzle through a supply conduit whose cross section isconsiderably larger that the complete area of the free passage openingof the exit gap of the wideslot nozzle.

The method according to the invention and the device according to theinvention, with which the set object is to be achieved, are defined inthe independent patent claims.

The device according to the invention and the method according to theinvention are suitable for all types of textile fibres, or for thetextile sheet material manufactured therefrom, preferably for thefibrillation of fine and light fabrics in a gentle manner.

The invention envisages that the high pressure fluid as a continuousfluid curtain impinges over the whole width and on at least one side ofthe continuously conveyed textile sheet material from the wide-slotnozzle. Such a wide-slot nozzle can be manufactured simply andinexpensively. The shape of the exit gap of the wide-slot nozzleprevents, on account of its larger special dimension and—in comparisondiscrete bores—its continuous exit opening, a blocking of the highpressure fluid by way of contaminations. A further advantage of theuninterrupted, gap-shaped exit opening lies in an absolutely uniformfluid curtain with which the web-like textile sheet material isimpacted. Interruptions in the fluid curtain by way of defects of thenozzles due to design do not occur.

Advantageous fibrillation results are obtained in that the fluid issupplied to the wide-slot nozzle at a pressure of 25 to 70 bar and therunning textile sheet material at the impinging location of the fluid issupported by a smooth, preferably impermeable support surface, inparticular in the form of a rotatable roller.

The high pressure fluid, by which means the fibrillation is effected,may usefully consist mainly of water, to which if required additionalsubstances may be added. These are to simplify or improve thefibrillation and are preferably swelling agents for cellulose-containingfibres. As such alkaline solutions are particularly suitable, such ase.g. sodium hydroxide, or sodium carbonate solutions. The methodaccording to the invention may be carried out particularly simply whenthe fluid mixed with air is led to the wide-slot nozzle.

The delivery of a continuous fluid curtain is effected preferably by wayof a wide-slot nozzle, whose exit gap for the fluid may be infinitelyadjusted in a width between 0.05 mm and 1 mm, preferably from 0.08 mm to0.15 mm. Also the mounting of the wide-slot nozzle on pivotable arms hasshown to be particularly suitable in order to achieve an outstandingfibrillation result. By way of this measure, the angle of impingment,which is spanned between the fluid curtain and the textile sheetmaterial, may thus be infinitely adjusted. The angle may roughly lie inthe region of 40° to 150°, preferably 60° to 120°.

The distance between the exit gap of the wide-slot nozzle and theimpinging location on the textile sheet material should preferably notexceed 200 mm, advantageously it should not be larger than 150 mm. Thisis relevant because too large a distance causes pressure losses of thehigh pressure fluid at the impinging location and by way of this leadsto an unsatisfactory fibrillation.

The impacting of the continuously supplied, web-like sheet material maybe carried out advantageously when the fluid supply conduit opens intoone end of the broad-slot nozzle and to the other end there is connecteda return conduit for the fluid. With this connection on both sides, thefluid may be delivered in a circuit, by which means an essentiallyuniform fluid pressure over the whole length of the broad-slot nozzlemay be achieved and any occurring deposits or incrustations may be sweptaway.

In order to achieve an adequate and uniform supply of fluid and constantfibrillation over the whole gap length, according to the invention thecross section of the supply conduit for the fluid is considerably largerthan the total cross section of the exit gap.

By way of these, under all operating conditions always considerably morefluid may be delivered to the wide-slot nozzle than this lets through.Thus the ratio of the area of the tube cross section of the supplyconduit of the nozzle to the total area of the passage opening of theexit gap should be at least 30 to 1, preferably 80 upto 100 to 1, orlarger. With an exit gap with a total area of 70 mm² to 400 mm² fromthis there results a tube cross section for the supply tube with a totalarea of at least 2100 mm² to 40000 mm².

The device for fibrillating according to the invention comprises furthera drive means for guiding the textile sheet material under the wide-slotnozzle and a drive and tensioning device for the further transport ofthe textile sheet material.

Embodiment examples of the invention are hereinafter described in moredetail by way of the drawings. There are shown:

FIG. 1 a schematic vertical section through a machine for fibrillating aweb-like, textile sheet material,

FIG. 2 a schematic plan view of the machine of FIG. 1,

FIG. 3 a schematic representation of a fibrillated fibre, for example acellulose fibre,

FIG. 4 a perspective representation of a wide-slot nozzle operated in acircuit and

FIG. 5 a schematic representation of a fibrillating device which isoperated with a fluid connection on one side.

The machine represented in FIGS. 1 and 2 contains a rotatable roller 1with a smooth, impermeable surface which is moved by a drive motor 2.The roller 1 supports and guides a continuously conveyed, web-like,textile sheet material 3, in particular at the impinging location 4 of ahigh pressure fluid.

The impacting of the continuously conveyed textile sheet material 3 withhigh pressure fluid is effected as a continuous fluid curtain 14 overthe whole width of the material 3 by way of an infinitely adjustable gap5 of a wide-slot nozzle 6. The width of the gap 5 of the wide-slotnozzle 6 is preferably adjusted in the regions between 0.05 mm and 1 mm.The distance of the wide-slot nozzle 6 to the guide roller 1 as a ruleis not more than 20 mm and in this embodiment example is 8 mm. The fluidis supplied to the wide-slot nozzle 6 with a pressure in the region of25 to 70 bar. The pressure is directed principly to the nature and thetransport speed of the textile sheet material 3. The impinging angle αof the fluid onto the sheet material 3, measured between the fluidcurtain 14 and the movement direction of the sheet material 3 at theimpinging location 4, may usefully be adjustable. The adjustability maybe achieved in that the wide-slot nozzle 6 is held on pivoting arms (notrepresented) which are pivotable about an axis which essentiallycoincides with the impinging line. By pivoting the arms holding thewide-slot nozzle 6 this may then be adjusted somewhat between a position6.1—impinging angle α about 120°—and a position 6.2—impinging angle αabout 60°. The adjustability of the impinging angle α may however alsobe achieved in that the roller 1 is mounted on pivoting arms which arepivotable about an axis essentially coinciding with the impinging line4.

Generally the impinging angle α lies in a region of 40° to 150°,preferably in the region of 60° to 120°.

In the embodiment example at a distance to the rotatable roller 1 thereis installed an identical combination of a rotatable roller 7 with asmooth, impermeable surface, which is moved by a drive motor 9, and awide-slot nozzle 8. Also in this combination the continuously conveyed,textile sheet material 3 however on its opposite side, is impacted at animpinging location 11 with a high pressure fluid curtain 14 which isproduced through an infinitely adjustable gap 10 of the wide-slot nozzle8. Also the wide-slot nozzle 8 may be pivotable between end positionswhich correspond to an impinging angle α of 120° (position 8.1) and 60°(position 8.2).

Furthermore the machine has means for moving a web-like, textile sheetmaterial 3 into contact with the circumference of the first roller 1 andthe second roller 7. To these means there belongs an inlet drive means12 with conveying rollers drivable by a motor 15. The drive means 12accommodates the approaching textile sheet material 3 and conveys isbroadly over the rotatable rollers 1 and 7. An outlet drive andtensioning means 13 with a drive motor 16 broadly pulls the textilesheet material 3 from the roller 7. The cooperation of the drive means12 and 13 produces a movement speed of the textile sheet material as arule between 0 m/min. and 30 m/min., preferably between 5 m/min. and 20m/min.

The arrangement as is shown, is such that the high pressure fluidcurtains 14 exiting from the wide-slot nozzles 6 and 8 impinge in eachcase on one of the two sides of the running textile sheet material 3over its whole width and cause fibrillation of the fibres.

The inlet drive means 12 and the outlet drive and tensioning means 13can be regulated by the man skilled in the art such that in the textilesheet material 3 between the two means 12 and 13 there prevails atension force which is approximately between 0 and 500 N per cm width ofthe textile sheet material 3 so that the high pressure fluid producesthe desired fibrillation effect.

The positions of the wide-slot nozzles 6 and 8 correspond to thepositions 6.2 and 8.1 respectively in FIG. 1.

The high pressure fluid curtain consists as a rule at least for the mostpart of water. The water may advantageously serve as a carrier fortreatment chemicals, in particular for swelling agents, which withnatural fibres in particular with cellulose-containing fibre materialsenlarge and/or soften the fibre surface. As swelling agents which arepresent dissolved in the water, for example alkaline solutions (NaOH,sodium carbonate) and alcoholic solutions are to be considered.

In the described manner textile sheet material of all types may befibrillated—fabrics, knitted fabrics, woven fabrics, nonwoven fabrics,and specifically of natural as well as of synthetic fibres.

FIG. 3 shows schematically a fibrillated cellulose fibre C, which is acomponents of a textile sheet material which is not shown here and istreated in the described manner. Fibrils F project from the fibre C.

The perspectively represented cutout shown in FIG. 4 and 5 shows therotary roller 1 with a smooth and impermeable surface, which supportsand guides the web-like, textile sheet material 3 and which is driven bya drive motor 2. In the embodiment form as is shown in FIG. 4 the fluidis guided through the wide-slot nozzle 6 in the circuit. A fluid supplyconduit 27 in which there is arranged a pump 19 opens into the one endof the wide-slot nozzle 6, and the other end of the wide-slot nozzle 6is connected to a return conduit 18. The supply and removal conduits 17and 18 have a diameter range of DN 20 mm to DN 200 mm, and thus apassage area of 300 mm² to 30000 mm². The ratio of the total area of thepassage opening of the supply conduit 17 to the passage area of thewide-slot nozzle 6 is thus about 100:1. (The total area of the passageopening is computed from the length of the opening multiplied by thewidth of the opening at the narrowest location of the nozzle crosssection).

The pump with a delivery output of 750 l/min ensures that an adequatefluid quantity is delivered and impacts on the impinging location 4. Thepump 19 serves the pumping around of the fluid in the circuit. As afluid water is used which is supplied through a conduit 20. To theconduit 20 there is connected a metering means 21 which metersadditional substances and/or air to the supplied water.

In FIG. 5 the wide-slot nozzle 6 with a fluid supply 17 on only one sideis shown. The high pressure fluid is in this case not pumped in thecircuit.

What is claimed is:
 1. A method for fibrillating a continuously conveyedtextile web, said method comprising steps of delivering a continuouscurtain of fluid against the entire width of at least one side of thetextile web by means of a wide-slot nozzle having an exit gap, andsupplying said fluid to the wide-slot nozzle via a supply conduit whosecross-section is equal to 300 to 100 times the total area of the area ofthe exit gap of the wide-slot nozzle.
 2. A method according to claim 1,wherein the fluid is supplied to the wide-slot nozzle at a pressure of25 to 70 bar.
 3. A method according to claim 1, wherein the web issupported by a smooth, impermeable support surface where it is impingedby said fluid.
 4. A method according to claim 1, wherein the wide-slotnozzle has a fluid connection on both its lateral sides.
 5. A methodaccording to claim 1, wherein the distance between the exit gap of thewide-slot nozzle and the textile web is not more than 20 mm.
 6. A methodaccording to claim 1, wherein the fluid consists essentially of water.7. A method according to claim 1, wherein the fluid consists of waterand swelling agents for natural fibers.
 8. A method according to claim1, wherein the fluid is directed at the web at an impinging angle ofbetween 40° and 150°.
 9. A method according to claim 1, wherein thefluid is mixed with air before it is supplied to the wide-slot nozzle.10. A device for fibrillating a textile web by means of a high-pressurefluid, said device comprising means for continuously conveying the web,a wide-slot nozzle for delivering a continuous fluid curtain onto theweb and a supply conduit for supplying said fluid to the wide-slotnozzle, wherein the supply conduit has a cross-section area 30 to 100times the free passage opening of the exit gap of the wide-slot nozzle.11. A device according to claim 10, wherein the supply conduit has across-section which is equal to 80 to 100 times the total area of thefree passage opening of the exit gap of the wide-slot nozzle.
 12. Adevice according to claim 10, wherein the total area of the free passageopening of the exit gap is between 70 mm² and 400 mm² and thecross-sectional area of the supply conduit is between 2100 mm² and 40000mm².
 13. A device according to claim 10, further comprising a rotatableroller having a smooth, impermeable surface for supporting and guidingthe web wherein it is impinged by the liquid.
 14. A device according toclaim 10, wherein the web conveying means includes a drive means forguiding the web past the wide-slot nozzle and a drive and tensioningmeans for further transporting the textile web.
 15. A device accordingto claim 10, further comprising means for continuously adjusting thewidth of the exit gap of the wide-slot nozzle.
 16. A device according toclaim 10, further comprising pivotable arms supporting the wide-slotnozzle in such a way that the impinging angle of the fluid against theweb is continuously adjustable in the range of 60° to 120°.
 17. A deviceaccording to claim 10, wherein the fluid supply conduit opens into oneend of the wide-slot nozzle and further comprising a return conduitattached to the other end of the nozzle.
 18. A device according to claim10, further comprising means for metering additional substances into thehigh pressure fluid supplied to the wide-slot nozzle.